Slippers



Aug. 11., 1970 Filed A ril 10. 1968 w.. MITCHELL E AL SLIPPERS 4Sheets-Sheet 1 INALEE 5 K%%f W JAMES G. MITCHELL Aug 11, 1970 w. rrcETAl; 3,523,378

I SLIPPERS 4 Sheets-Sheet Filed April 10. I968 M/VE/WORS INALEEG.MITCHEL..L JAMES G.MITCHELL ymfi/ FIGS Aug. 11,1970 w, rr ETAL3,523,373 I SLIPPERS Filed April 10, 1968 I 4 Sheets-Sheet 4 INVENTORSH2 WINALEE 5. MITCHELL JAMES c. MITCHELL BY flm? ATTORNEY 3,523,378SLIPPERS Wmalee G. Mitchell and James G. Mitchell, both of 205Farnsworth Road, Water-ville, Ohio 43566 Filed Apr. 10, 1968, Ser. No.720,016 The portion of the term of the patent subsequent to Feb. 11,1986, has been disclaimer] Int. Cl. A43b 3/10 US. Cl. 362.5 4 ClaimsABSTRACT OF THE DISCLOSURE Slippers having an upper joined to a lowerblank of elastomeric sheeting material which increases in width but themarginal edges thereof taper inwardly and upwardly toward the heel wherethe left and right sides are joined in a heel seam which is at leastpartly forwardly inclined. Also, a method of making such slippersincluding the steps of simultaneously cutting and bonding an upper witha lower blank having lateral edges which, in the rearward direction arefrom about parallel to divergent, folding the lower blank on about itslongitudinal axis and bonding the folded left and right sides togetheralong a heel seam which is at least partly forwardly inclined.

RELATED APPLICATIONS This application discloses subject matter which iscommon to it and to our prior copending applications Ser. No. 451,181,filed Apr. 27, 1965, and 634,426 filed Apr. 24, 1967.

BACKGROUND AND OBJECTS Heretofore there has been a need for strong,sanitary and inexpensive footwear and for efiicient methods ofmanufacturing it. This need has been met to a substantial extent by thefootwear and production methods disclosed in our US. Pat. 3,238,079.Plastic slippers fabricated in accordance with the teachings of thatpatent are enjoying widespread and steadily increasing commercial usewhere paper slippers (or none at all) were used previously. Consideringthe thin guage of plastic foam sheeting which must be used to permiteconomical pricing, and the fact that the slippers are held in place onthe wearers foot, in part, by internal elastic tension in the plasticfoam material, they display a surprising degree of resistance to tearingwhile in use. This is particularly true of slippers made in small andmedium sizes andto a lesser extent of larger silppers. However, in thecase of the largest men's sizes some difiiculties have been experienced.

With the retention of the slippers in place on the wearers footdepending as its does on the stretching of the plastic material, theslippers must be of smaller dimensions than the size of the foot forwhich they are intended. It has been found however that when slippersintended for the largest sizes of feet are made small enough to providethe requisite internal tenison to keep them in place, they do notprovide sufficient coverage of the wearers heel, and when made largeenough to adequately cover the heel are not stretched sufliciently tokeep them securely in place. Accordingly a need remains for improvementsin plastic slippers and methods of making them which make available bothadequate coverage for the wearers heel and satisfactory retentionqualities.

It is a principal object of this invention to fulfill this need. Otherobjects of the invention will be apparent to those skilled in the artfrom the following description of our footwear and method inventions andcertain nonlimiting embodiments thereof.

United States Patent 'ice BRIEF SUMMARY OF THE INVENTION The foregoingobject can be met with a slipper comprising an upper attached to a soleor lower blank of elastomeric sheet material, the marginal edges ofwhich taper upwardly and inwardly at points successively closer to theheel. At the heel, the left and right sides of the lower blank join oneanother in a generally upright seam which is at least partly forwardlyinclined for gripping the wearers heel. This seam and such other seamsas may be required to join the upper to the lower blank may be basedupon any effective method of joinder, such as sewing, cementing, thermalsealing, induction sealing and the like. The term elastomeric isintended to include any material, natural or synthetic, characterized byflexibility and stretchy elasticity, and is preferably, though by nomeans essentially, spongy; that is, the material preferably includescellular structure. A preferred example of such a spongy material isopen-celled polyurethane foam, a synthetic elastomeric material whichmay be produced by blowing a' polyester resin with a diisocyanatecompound. Such materials are readily available commercially in sheetform from a number of suppliers and are readily amenable to the variousmethods of joinder described in our US. Pat. 3,238,079, the disclosureof which is hereby incorporated by reference.

Generally speaking, the method we have invented involves a series ofsteps, including: bringing a first layer of heat-scalable elastomericmaterial and a substantially wider second layer of heat-scalableelastomeric material into face-to-face relationship with one edge ofeach layer being substantially aligned with one edge of the other toprovide in said second layer a covered portion which is in face-to-facerelationship with the first layer and an exposed portion which is not inface-to-face relationship with the first layer; in a first bondingoperation, uniting said layers to form therein the toe portion of aslipper by subjecting the first layer and the covered portion of thesecond layer to sufiicient heat and pressure to form a heat-sealed bondbetween them in a first narrow region having two branches extending awayfrom said substantially aligned edges and spaced apart from one anotherby approximately the width of the toe and instep of a human foot ofpredetermined size; while still under the pressure' bf said firstbonding operation, cutting the material of the first and second layersalong the first narrow region; cutting the exposed portion of the secondlayer along lines extending from the ends of said branches in adirection away from the aligned edges of the layers to form a blankhaving its longitudinal axis extending away from the said aligned edgesand separating the blank from the remainder of the material of saidlayers; folding the material of the exposed portion of the second layerinthe blank on either side of the longitudinal axis thereof intoface-to-face relationship in a plane generally perpendicular to thefirst narow region; and, in a second bonding operation, forming the heelof a slipper by subjecting the folded exposed portion of the secondlayer to sufficient heat and pressure to form a heat-sealed bond in asecond narrow region which is spaced longitudinally of said blank fromsaid first layer and is in a plane generally perpendicular to said firstregion.

Although the terms first layer and second layer may in some contextsconnote two separate pieces of material, these terms are used herein notonly with that connotation in mind, but also to refer to diiferentportions of the same piece of material which has been folded upon itselfto form two or more layers.

Heat-scalable material refers to any supple synthetic polymeric webwhich may be bonded to itself and to other materials by coalescence ormelting together under the action of pressure and heat, whether inducedthermally or electronically.

When it is stated that edges of the layers are substantially aligned, itis not required that these edges exactly coincide or even be preciselyparallel, although such is definitely preferred from the stand-point ofproduction efiiciency and avoiding waste of material; it is sufii cientif the edges be approximately parallel and adjacent to one another.

The face-to-face relationship referred to above does not require thelayers to contact one another over their entire adjacent surfaces. Forinstance, the layers may be closely adjacent to one another butseparated prior to bonding by a layer of thin, loosely woven cloth orscrim material through which the heat-sealable materials of therespective layers may flow during the bonding operation to form a seal,thus enveloping and bonding the cloth or scrim material in the sealbetween the layers and enabling it to serve as a liner in the finishedslipper. Thus, it is apparent also that the method as stated abovecomprehends the formation of slippers having two or more layers of oneor more different materials. The usual practice however will be toemploy a single kind of synthetic polymer foam webbing material in aconstruction which includes just a first and second layer, except thatthe first layer may, for strengthening and/or decorative purposes befolded upon itself in a manner to be described hereinafter.

The extent to which the second layer is wider than the first isdependent upon how much of the wearers instep it is desired to havecovered by the slipper, and how much waste can be tolerated in themanufacturing process. Generally, the second layer will be about 1.5 toabout times as wide as the first layer, measured between the first andsecond regions.

The two branches of the first narrow region refer to those portions ofthe heat seal between the first and second layers which extendrespectively along the right and left sides of the toe portion of theslipper. These branches may meet in the manner of the arms of a V if apointed toe is desired or may meet in the manner of the arms of a U orany other suitable manner.

The aforesaid first and second regions may be continuous ordiscontinuous, as it is known to produce heat seals which are continuousor which are closely adjacent increments of sealed materiallongitudinally interspersed with unsealed or only partially sealedmaterial. When the first and second layers are of different colors, thisprovides a vari-colored seal of pleasing appearance.

Although the cutting of the blank should take place while the firstregion is still under the pressure of the bonding operation, this shouldnot be construed as requiring that the bond should be complete at thetime cutting takes place. The cutting may occur before, during or afterformation of the bond. The term cutting is intended to be construedbroadly to cover cutting, shearing, tearing and generally any othersuitable mode of separating the blank from the remaining portions (e.g.waste) of the first and second layers. The cutting along the firstnarrow region may be performed along the outer edge of the region, oreven within the region, in which event part of the seam remains with theblank and the remainder goes with the waste. This cutting operation isbest though not essentially--performed simultaneously with the cuttingof the exposed portion of the second layer to complete the cutting ofthe blank in one operation.

The lines along which the exposed portion is cut pref erably divergefrom one another as they extend away from the toe portion. Experimentshave shown that the lines may converge some, but as the angle ofconvergence increases, the height and therefore the grippingcapabilities of the heel are reduced. Therefore, it is preferred thatthe angle between the aforesaid lines he in the range of about 0 toabout 90.

4 BRIEF DESCRIPTION OF THE DRAWINGS Illustrative, non-limiting preferredembodiments of the present footwear and method inventions are depictedin the accompanying drawings, in which:

FIGS. 1 through 3 are side, front and rear elevations (non-wearingposition) of a novel slipper corresponding with the invention;

FIGS. 4 and 5 are perspective (wearing position) and top plan(non-wearing position) views of the aforementioned slipper;

FIG. 6 is a partly sectional schematic illustration of a method by whichplastic slippers may be produced;

FIGS. 7 and 8 are sectional views taken along section lines 7-7 and 88,respectively, in FIG. 6;

FIG. 9 is an enlarged detailed view of a portion of FIG. 6;

FIG. 10 is a top plan view of a fragment of the material used in theprocess as it appears when clenched in the die shown in FIG. 9;

FIG. 11 is a perspective view of apparatus for forming the heel seam andof the lower blank folded for insertion therein; and

FIG. 12. is a showing of the slipper after withdrawal from the apparatusof FIG. 11, the material removed by such apparatus being shown inphantom outline.

DESCRIPTION OF PREFERRED EMBODIMENTS (1) Slipper The non-limitingillustrative embodiment of a slipper shown in FIGS. 1-5 includes anupper 20 having a foldedover portion 21 at its rear edge 22. Thefolded-over portion 21 provides extra strength, but may be omitted. Insuch case, edge 22 need not be straight and may have various decorativeoutlines, such as wavy, curved or serrated.

The sole or lower blank 23 is joined to the upper along a seam of fusedmaterial 24 such as is formed by a thermal heat-sealing and cuttingprocedure and apparatus of the type hereinafter described. Forconvenient description, the lower blank is referred to hereinafter ashaving a toe or covered portion 26-which is that portion which coincideswith and is covered by the upperand a rear or exposed portion 27whichincludes all of the lower blank to the rear of rear edge 22 of theupper. The toe portion of the lower blank, and the upper are generallyhorizontally disposed and have a width and a shape which are generallyconformable to those of a human foot, but the shape may be varied freelyin accordance with the dictates of convenience and fashion. When theupper is provided, with a folded-over portion 21, it is beneficial tohave that portion joined to the remainder of the upper and to the lowerin seam 24 as shown in FIGS. 1-5. In any event, the rear edge 22 of theupper extends from one lateral edge 28 to the other lateral edge 29 ofthe lower blank and is free of attachment to said blank except at saidlateral edges, thereby providing a sort of pocket for insertion of thewearers toes, which pocket may be open, closed, rounded fiat or pointedat the toes, as desired. The longitudinal position of rear edge 22 maybe moved forward or backward as desired so long as adequate room forinsertion of the wearers foot and satisfactory coverage of the toes areprovided.

In accordance with the preferred embodiment of the invention, the lowerblank 23 has a rearwardly divergent Width; that is, the width of thematerial in the blank, measured flat, increases when measuredperpendicular to the longitudinal axis of the slipper at a plurality ofpoints successively closer to the heel. Such divergency may exist onlyin the exposed portion of the lower or in both the exposed portion andcovered portion, the latter being the preferred mode which is disclosedherein. The angle of divergence, measured between the marginal edges ofthe flattened lower blank, should be substantial, e.g. at least about10. Angles of divergence of about 10 to about 45 are preferred, with anangle of about l8-20 being considered best. Larger angles can be used,but the amount of waste material produced in the making of the slippersincreases as the angle is increased. Thus, when we state that thecontemplated range of the angle of divergence is from about 10 to about90, there is no intention of ruling out larger angles. About' 90 isrecited merely as the angle beyond which the economic penalty associatedwith widening the angle of divergence is believed sufficiently great asto make any further increase undesirable from the stand-point ofefiicient manufacturing practice.

It is a feature of the invention that there is, in the rear portion ofblank 23, a tapering inwardly and upwardly of the lateral edges 28 and29 toward a vertical plane 30 (FIG. 3) which passes through the slipperabout at its longitudinal axis. The material of the exposed portion ofthe lower bends upward as it passes through this plane with the radiusof curvature in the bend gradually increasing (while the slipper is notbeing worn) at points along the axis successively closer to the heel. Atthe extreme rear of the exposed portion the left 33 and right 34 sidesof the lower blank join and are bonded with one another along a heelseam 31. A portion 32 of this seam is inclined forwardly to grip thewearers heel. The remainder of the seam may incline backwardly orforwardly to provide a smooth-fitting heel or various decorativeeffects. Preferably, the heel seam 31 is in the form of a smooth curvewhich, at. its lower end, lies approximately tangent to the bottom ofthe lower blank, and at its upper end, intersects the marginal edges 28and 29 at an acute angle, said angle being measured with the slipperfolded along its longitudinal axis with the inner surfaces of sides 33and 34 in face-to-face contact.

The slipper of the herein disclosed preferred embodiment is furthercharacterized in that the lower blank 23 extends as a single, continuouslayer of elastomer foam material from one marginal edge to theother, sothat one and the same piece of material serves as the sole, sides andheel of the slipper. Because said layer is preferably formed into a heelportion by a generally upright single seam which unites the material onthe left side of the longitudinal axis of the slipper to that on theright, the sides and rear of the slipper can be formed from the foldedblank in a single operation without the necessity of any horizontalseaming, as is required in most conventional shoe, slipper and moccasinconfigurations.

In a commercial embodiment of the herein described slipper, the radiusof curvature of the leading edge of the toe portion is about 2". Theangle of divergence of the lateral marginal edges of the upper andlower, measured with the lower blank flattened against a planar surface,is about 18-20. The upper, measured from the front to the rear edge, atthe longest point, is about long. The folded over portion is about 2"long. The width of the upper, measured along its rear edge is about 5%".The over-all length of the slipper, measured along its longitudinal axisis about 12". The radius of curvature of the heel seam is about 4 /2".

Persons skilled in the art will readily recognize that slippers of theabove-described type may readily be fabricated by hand or by machine andby a variety of methods. However, We have found that they can bemanufactured with particular efficiency by the method of the presentinvention, an illustrative preferred embodiment of which will bedescribed below.

(.2) Method A preferred embodiment of the above-described method is bestillustrated in FIG. 6, wherein a first strip or layer of thermoplastic,heat-sealable polyurethane open or closed cell foam 40, preferably theformer, is removed from its storage roll 38 and advanced by rollers 62to a folding station 81. The advancing strip of foam material 40 firststrikes the upright angular element 82 and approximately of the width ofthe material is raised in an upright, angular relationship to theadvancing main portion of strip 40 as shown in FIG. 7. Immediatelythereafter, the upright portion 40A is folded over upon the main portionof strip 40 as illustrated in FIG. 8. This folding is accomplished bythe use of form 83, and once established, the advancing strip itselftends to serve as its own guide means to provide a double layeredadvancing strip of material, the double layer extending approximately Vathe width of the advancing strip.

Simultaneously, a second strip or layer 48 of the same material isadvanced from storage roll 47 by guide rollers 84 and 85, and is broughtinto face-to-face contact with the double-layered strip 40 at feedrollers 58 and 59. The second strip 48 may be cellular or non-cellular,although foam material is definitely preferred, since a more comfortableslipper will result. Alternatively, the first sheet may be non-cellularmaterial and the second cellular. It is also possible to provide adouble sole in the slipper. For instance, the upper would be either ofcellular or non-cellular material and the lower would be in two layers,one of foam, the other of non-cellular material. There would be nodeparture from the present invention in making such modifications, sincethe substitution of cel lular material for non-cellular material or thereplace ment of a single strip of one kind or the other with two strips,one of each kind, would not alter the sequence or relationship of theessential steps in our process. Therefore, although we will proceed witha description which refers to both the first and second strips as beingof foam material, no intention to exclude any of the above modificationsor others should be inferred.

The strips 40, 40A and 4-8 are preferably advanced through cutting andsealing station 86 incrementally. That is, their advancement occurs in aseries of successive, left-to-right longitudinal movements of equallength, each movement being followed by a short period in which thestrip is stationary. The cutting and sealing station functions each timethe material comes to rest, resulting in the formation of a series ofslipper blanks that are spaced apart from one another along the strip ofmaterial. However, those skilled in the art will readily recognize thatthe above method may be practiced with a variety of equipment and indifferent modes. Thus the material may be advanced relativelycontinuously with the fabricating steps being preformed by flyingpunches, cutters and dyes. Or, in the preferred embodiment, aspreviously indicated, material may be advanced incrementally asillustrated in FIG. 6.

At the cutting and sealing station 86, there is a stationary lowersealing die '67 having an upwardly disposed horizontal die face 51 asillustrated in FIGS. 6 and 9. This die is provided with a heatingelement 53 by means of which the die face 51 can be raised to the fusiontemperature of the thermoplastic foam material in strips 40 (including40A) and 48. Directly above die face 51 and in registry therewith is asubstantially identical downwardly disposed horizontal die face 50 ofupper sealing die 66 as illustrated in FIGS. 6 and 9. Die 66 is providedwith heating elements 52, similar to heating elements 53.

Unlike lower die 67, upper die 66 reciprocates vertically. By means ofany suitable reciprocating motor means 57, the upper die 66 is pressedfirmly into contact with the strip 40 and 40A each time it comes to restand is retracted before the material begins to move again. Thus, duringthose periods when the strips 40 (including 40A) and 48 are stationary,they are compressed for a time between the dies 66 and 67.

A shearing-type cutter 56 is associated with the upper die 66. As willbe noted from FIG. 9, the cutter is fitted closely about the entireperiphery of die 66. Because the die 66 and 67 have vertical walls andmeet in substantially perfect registry, the cutter 56 can separate thematerial clenched in the die from that lying outside of it.

In order to more fully disclose how the cutting and sealing operationmay be carried out, reference is now made to the enlarged figure, FIG.9, showing additional details of the cutting and sealing stationschematically represented inFIG.-6.

As show in FIG. 9, the cutter 56 is generally in the shape of aninverted box which partially encloses upper die 66. The cutter includesa base portion 70 attached to the motor means 57. Side walls 69 dependfrom base 70, and a hardened cutting insert 56 is secured in the loweredge of side Wall 69. This insert 56 conforms to the exterior surface ofdie walls 75 and 76 of the upper and lower dies 66 and 67 and surroundsthe upper die. The upper die is suspended within the cutter assemblywith the aid of bolts 7l1 which pass through holes 72 in cutter base 70,and threadedly engage the upper die backing members 73. The bolts 71have heads 74 which hang on the upper surface of the backing member.Springs 55 are 'wound about the bolts between base 70 and the upper diebacking member. The function of these springs will become apparent asthe description unfolds.

The normal condition of the dies, that is, their condition while thestrips 40, 40A and 48 are advancing, is open. The dies normally havesufficient clearance between them to permit the full thickness of thestrips or layers 40 (including 40A) and 48 to advance between themwithout catching. The stroke of the press actually exceeds theaforementioned clearance to the extent necessary to drive the cutterinsert 56 at least partially below the surface'of lower die face 51.However, since the springs 55 are interposed between the cutter base andthe upper die, and because the cutter insert normally rides above upperdie face 50, upper die 66 must come to rest and the springs 55 must becompressed to a significant extent before the cutter insert 56 dropsbelow the lower die face 51.

When the strips 40 and 48 come to rest, the upper die closes down ontothe lower die. The size and strength of the springs 55 are sufficientlygreat to insure that as the press closes, those portions of strips 40and 48 which are between the die faces 50 and 51 will be substantiallyand completely crushed therebetween, before the springs 55 yield to anysignificant extent under the pressure from motor 57. Thus, effectiveoperation of the cutter is prevented until the strips are thoroughlyimmobilized by being clenched between the die faces. FIG. 9 illustratesthat point in the operation of the cutter die assembly when the foammaterial is collapsed but just before the springs yield.

The condition of the strips 40 and 48 when clenched in the dies isfurther illustrated in FIG. 10. This figure shows the material from thetop with the upper die removed. The aligned edges of strips 40 and 48are indicated by reference numerals 110 and 111 respectively. First,second and third hatched areas 112, 113 and 114, hatched with inclinedlines, and fourth, fifth and sixth hatched areas 115, 116 and 117,hatched with vertical lines, represent the areas of the layerscompressed between die faces 50 and 51. Hatched area 112 is the top of anarrow region 64 (FIG. 9) in which the die faces fully collapse theelastomeric foam for coalesing and thermally bonding them with oneanother. A vertical clearance (e.g. 0.020") is provided between thoseportions of the die faces above and below hatched areas 115, 116 and117, so that the dies will not fully collapse the exposed portion oflower layer 48 in these areas. The clearance is provided merely byrelieving (making upper die higher and lower die lower) by 0.010" in theindicated areas. Adjacent hatched areas 113 and 114, the die faces areat the same elevation as the adjacent area 112, for the purposeof-helping to keep the relieved portions of the die in parallel-planarrelationship.

The collapsing of the layers 40 and 48 in region 64 under area 112, andthe transmission of heat to the layers at a controlled temperature for apredetermined time interval (e.g. 500 F. for about /1 second) unites thelayers to form the toe portion of a Slipper in the lower blank. Theregion 64 may be regarded as including two branches 119 and 120extending away from aligned edges and 111 of the layers on either sideof the axis 121 of the lower blank.

In accordance with the present embodiment of the invention, there isonly one layer (48) of material under areas 115 and 116 and thus no needto bond anything together. However, where there are to be two lowerlayers, such as when the sole of the slipper is to comprise for instancea layer of impervious polymeric film as the sole and a layer ofelastomeric foam as a cushion insole, it could be desirable to omit therelieving of the die faces in areas so as to unite the edges of the soleand insole. In any event, whether those portions of the die facescorresponding to areas 115 and 116 are relieved or not, they serve toimmobilize the adjacent material of the layer or layers to facilitatethe cutting operation.

The cutter 56 (FIG. 9), which extends all the way around the upper die,moves downward to sever the material within the die from that outsidethe die. The line of cutting is indicated by dashed line 122 in FIG. 10.The cutting line extends around the outer edge of the first region 64,passing through both layers 40 and the covered portion of layer 48. Thecutting line or lines 122 extend from the ends of the two branches 119and 120 of region 64 in a direction away from the aligned edges 110 and111 of layers 40 and 48, thus traversing the lower layer 48 and thenextending parallel and adjacent to the opposite edge 123 of the layer 48and meeting at the "rear 124 of the blank. The cutting is preferablyperformed outside the region, as shown herein. However, as alreadyindicated, cutting and sealing devices are known, such as thoseincluding a cutting wire centered along the face of a sealing die, whichcut within the bonded region, and the use of such would not constitute adeparture from the spirit of the invention.

Once both the cutting and sealing have been accomplished, the upper dieretracts by reversal of motor 57. As the dies open, the strips ofthermoplastic material again advance, and the completed slipper blank 63leaves the press and is separated from the remaining portions of strips40 and 48 as best illustrated in FIG. 6. These remaining portionsconstitute the waste products of the present method. It will be notedfrom FIG. 6 that some waste is left behind in the lower or second strip48 adjacent the heel end of the blank 63. Some waste should also be leftadjacent the toe, so that there is waste adjacent both the toe and heelends of the blank. This allows the progression mechanism, to bedescribed later, to withdraw the waste evenly from the cutting andsealing operation.

Each time the strips 40 and 48 come to rest, the abovedescribedsuccessive steps of closing the dies, forming a seal, cutting away wastematerial, opening the dies, further advancing the material, and bringingthe material to rest are repeated again and again on a continuous basis.

An optional added feature of the cutter and die assembly depicted inFIG. 9 is a pair of spring mounted plates 77, secured inside dies 66 and67 respectively with the aid of bolts 78. The bolts 78 threadedly engagethe aforesaid plates and pass through holes 79 in the die 66 and 67 andin their respective backing members 73 and 80. Between each of the diesin respective plate members are secured coil springs 87 which are woundabout the bolt 78 in which are slightly less compressable than theelastromeric foam material.

When each of the dies are open, each of the plate members 77 protrudesslightly from its die. When the die closes down upon the strips 40, 40Aand 48, the spring loaded plates exert pressure on the foam materialencircled by the die faces 50 and 51, although not compressing thelatter material to the same extent as the material in the region 64. Asa consequence of the relatively tight grip on the material and thesomewhat indirect and loose contact with the heating elements 52 and 53and die backing members 73 and 80, the plates 77 do not cause anybonding between the strips of thermoplastic foam material which isbetween them. Consequently, their sole function when the press is closedis to immobilize the material. In returning to their protrudingcondition when the die is open, the plates will wrest free the slipperand the waste material in the event that they stick to either of thedies thus facilitating their removal.

In order to practice our method and apparatus of the character describedabove, it is necessary to utilize some form of automatic mechanism foradvancing material through punching, sealing, and cutting stations. Anyeffective means for engaging the strips and moving them incrementally atthe same controlled rate and over the same controlled distance may beused to provide the force for advancing the material. It is desirablethat the force be applied directly to the strips both ahead of andbeyond the sealing and severing operation. This result can be obtainedwith the aid of any transport means which acts throughout some portionof the length of the strips, which portion traverses the cutting andsealing operation. Alternately means acting upon the strips at spacedpoints both ahead of and beyond the cutting and sealing station may beused. For instance, in the present embodiment (FIG. 6), the means actingupon the strips at spaced points both ahead of and beyond the cuttingand sealing rollers is a set of rollers. The set includes two pairs ofrollers, a first pair 58 and 59 ahead of said station and the secondpair 60 and 61 beyond said station. All of the rollers are driven by onecommon or several synchronous driving means 125, so that each pair actsat the same rate, with the same amount of force and moves the materialthrough the same distance as the other. The rollers 62, 84 and 85 mayalso be tied into the driving system if desired.

A complete system will also include suitable means for synchronizing theoperation of the motor 57 with the work-advancing mechanism. The mainobjective is to insure that the cutter-sealer mechanism will contact thematerial only when it is at rest. This objective can be easily obtainedthrough the use of electric rotary switchtype timer clocks or electronicsequence timers, hydraulic pumps, solenoid valves, limit switches andcontrol apparatus with which those skilled in the art are alreadyfamiliar. Therefore they have merely been indicated schematically in thedrawing.

The blank produced in accordance with the procedure depicted in FIGS. 6through is folded by hand along its longitudinal axis so that the outerends 91 and 92 of the lower blank are in registration with one another.The folded blank is then moved by hand in the direction of the arrow inFIG. 11 into the cutting and sealing mechanism 90. Guide rods 93, 94enable the operator of sealing and cutting station 90 to quickly andaccurately position the slipper blank within the cutting and sealingstation by providing horizontal and vertical registration for theslipper blank.

Cutting and sealing die 95 is formed on die plate 96 and meets inregistration with a similarly formed die (not shown) mounted on dieplate 97. The two dies are in perfect registry with each other, andprovide the contoured shape for the rear of the slipper illustrated inFIG. 12. Guide rods 93 and 94 perform the dual function of guiding theslipper blank into registry with the die surfaces and guiding die plate96 during its reciprocal motion.

After the operator has inserted the slipper blank into cutting andsealing station 90, hydraulic ram 97 is activated by suitable controlsto move die plate 96 laterally on guide rods 93 and 94 into contact andregistration with its mating die surface mounted on die plate 97. Indoing so, die 95 and the corresponding die on plate 97 crush portions ofthe slipper blank therebetween. Die plates 96 and 97 are heated by anysuitable means such as an electric resistance heater (not shown), andthe sealing takes place when the elastomeric material is crushedtogether in a second region 98 and absorbs sufficient heat from the diesto coalesce and form a bond. This coalescence is ideally carried to thepoint that for the most part the cellular structure of the materialbetween the die faces is virtually destroyed, leaving behind a pliable,non-cellular seam in region 98 which is illustrated in FIG. 12. Bondingof the strips does not occur to any significant extent outside of region98 because of the poor heat conductivity of the plastic foam.

Die and its matching die on plate 97 may be formed with cutting edgesthereon as illustrated at 99. When die plate 96 advances toward dieplate 97, the cutting edge 99, and the adjacent cutting edge mounted onthe die of plate 97, meet in registry and the force generated byhydraulic ram 97 severs the material along the trailing edges of thedies while region 98 is being heat sealed. Upon completion of thecutting and sealing operation, which is normally a matter of a fewseconds or fractions thereof, the hydraulic ram is retracted by means ofa suitable control. Hydraulic ram 97 is powered in and powered out bythe application of hydraulic pressure through hydraulic inputs 100 and101. It should be understood however that a pneumatic ram could beutilized as effectively as a hydraulic ram, and an electric solenoid orother reciprocating motor could also be substituted. It should also bepointed out, that although in the preferred embodiment, both the openingand closing of die plates 96 is under the control of the operator, theoperation is preferably made semiautomatic by provision of an automaticreturn of the die plates to open position after a predetermined timeinterval, thus causing the sealing station to function with a lesserchance of error in the sealing interval.

Although in the preferred embodiment, die plate 96 is the only moveablepart of the dies, it should be understood that a mechanism with floatingdye plates or one with a moveable die and a separate moving shearingmechanism, as previously described for the first cutting and sealingstation, could be employed. The latter is somewhat more complex but maypossibly function more dependably than the combined cutting and sealingdie faces 99. Alternately, both die plates 96 and 97 could be advancedto a center position.

The above preferred embodiment illustrated how the invention may readilybe practiced with thermal heat sealing apparatus. Our invention may alsobe practiced with electronic sealing apparatus. These two types ofapparatus, although they are both thermal in a sense are distinguishablewith regard to the matter of applying the heat to the work. In thermalsealing apparatus, the heat is transferred solely by direct conductionof heat units from a preheated dye directly to the material which thedye contacts under pressure. US Pat. 2,425,388 is an example of thistype.

In the so-called electronic type of apparatus, the heat is developed inthe material at least in part by subjecting the material to a highfrequency alternating field. An example of this type is found in US.Pat. 2,796,913. Electronic apparatus customarily includes auxiliaryheating means of the thermal type. In such a case the heat is applied tothe material partly by conduction and partly by induction. For example,see US. Pat. 3,026,233.

During the sealing operations of the present method, the foam materialis squeezed down by any suitable compression means to a fraction of itsuncompressed thickness in the region(s) where the sealing takes place.Any effective means of compressing the material may be used. In the caseof thermal sealing equipment, the member that transmits both pressureand heat to the material is ordinarily a metal-faced dye correspondingto the shape of the desired seam. In electronic equipment the membersbetween which the sheets of foam are squeezed often comprise a die whichis formed basically of metal that has a facing of fiberglass-reinforcedheat resistant polymer backed up by a layer of elastomeric materialintermediate the metal and the facing.

The severing or cutting operations may take place while the work is inthe grasp of the compression means or after it is released therefrom,the former mode of operation being preferred. The cutting means of bothsteps may be manual or mechanical, the latter being preferred forreasons of uniformity of operation, Speed and economy. Among theavailable alternate mechanical shearing means are the ones illustratedabove and various shearing dies, cutting dies and cutting wires. Some ofthe alternate cutting means are illustrated in U.S. Pats. 3,015,601,3,025,206 and 2,425,388.

From the above description of our methods, it is clear that they aresufliciently versatile to be practiced in a variety of types ofequipment, only a few preferred representatives of which have beenmentioned. Those skilled in the art will readily adapt this method totypes of apparatus not disclosed herein without departing from the stepsdescribed herein. The present method has the advantage of producingslippers with a minimum of handling of materials during and prior toproduction. It can be performed at a great rate of speed with a highdegree of product uniformity and few rejects. It is readily adaptable tomachinery in which gauged arrangements of sealing mechanisms andsevering means are used to turn out a plurality of slippers for eachcycle of machine operation.

Having described not only novel articles of manufacture and methods butalso apparatus for carrying out said methods, we wish it to beunderstood that our methods are not restricted to the particular designof slipper disclosed herein, nor is our slipper invention required to bemanufactured by the methods of manufacture disclosed herein, except tothe extent that such restrictions are clearly expressed in the appendedclaims. Therefore it should be understood Where a certain step isrecited in the appended method claims, reference should not be made tothe specification for the purpose of introducing limitations germain tothe products or exemplary apparatus disclosed herein and vice versa.

12 What is claimed is:

1. An article of footwear comprising: a sole member of elastomeric sheetmaterial having a toe portion, a heel portion, and marginal edgesextending from said toe portion to said heel portion; an upper memberattached to said toe portion by seams extending generally horizontallyalong said upper member and said marginal edges; said marginal edges ofsaid sole member tapering upwardly and inwardly at points progressivelyfurther from said toe portion; said upwardly and inwardly taperingportions of said sole member defining the left and right sides of theheel portion of said footwear; said upwardly tapering portions of saidsole member being joined together at the heel of said footwear in agenerally upright seam which is at least partly forwardly inclined.

2. An article of footwear as claimed in claim 1 wherein said uppermember further comprises a second layer of elastomeric sheet materialfolded upon itself to form a reinforced portion along its rearward edge.

3. An article of footwear as claimed in claim 1 wherein said uppermember is attached to said sole member by means of a heat seal.

4. An article of footwear as claimed in claim 1 wherein elastomericmaterial is an open-celled polyurethane foam produced by blowing apolyester resin with a diisocyanate compound.

References Cited UNITED STATES PATENTS 2,038,844 4/1936 Le Dorf 36102,463,296 3/1949 Moore 3610 2,803,894 8/1957 Morgan 36-9 X 2,952,9269/1960 Laven 36-10 X 2,971,278 2/1961 Scholl 36-9 3,299,540 1/1967Scholl 368.1 3,426,454 2/1969 Mitchell et a1. 362.5

ALFRED R. GUEST, Primary Examiner U.S. Cl. X.R. 36-10

